The production of broilers in the poultry industry involves a "grow out" stage in which many thousands of young chicks are delivered to a poultry house, where they are sheltered and provided with food and water through a growth cycle of about 6-8 weeks. The chicks are not individually caged, but area massed in the poultry house by the thousands. The poultry house may be provided with large openings along its length for ventilation, the openings being provided with curtains to control air in-flow and to maintain heat in the winter. Alternatively, the building may be totally enclosed and dependant upon mechanical ventilation for substantially all air exchange, in which case fans my be located at spaced positions along the length of the house. A plurality of the heaters are also normally provided for maintaining the temperature at a desire level. The heaters may be spaced along the length of one wall, preferably the wall opposite the location of the fans. Moreover, cooling is not usually provided.
For the first three weeks of life, chicks are not able to control their own body temperature, and thus, are very susceptible to changes in temperature within the poultry house. For this reason, the heaters are capable of maintaining the temperature level constantly high in the range of 85.degree.-95.degree. F. Supplemental heat from these heaters must be added during cooler weather, and during warmer weather, the houses must be well ventilated to prevent over heating.
In the poultry house, the entire floor normally is covered with a "litter" material, usually wood shavings, which remains in place for about a year before being changed. During that time, the litter accumulates a great deal of fecal matter, water, spilled feed, and the like, so that its nature and consistency gradually changes over that period of time. The condition of the litter directly affects the quality of the air in the poultry house and, to a large extent, determines the air quality. Accordingly, an important factor in determining the moisture level in the litter is the relative humidity of air within the poultry house. Furthermore, bird health and performance are directly related to the moisture level of the litter in the poultry house.
The operations of various heaters and ventilators in poultry houses was, in the past, controlled manually by an operator who made periodic measurements for subjective assessments of litter moisture level and interior temperature levels, with the operator being required to then experiment with the heating and ventilation controls and attempt to regulate the air quality on the basis of those measurements or assessments. Because the relationships are complex and because the operator only makes periodic measurements and adjustments, such manual systems lead to wide, often harmful, fluctuations in temperature and humidity. This predicament presents an almost insurmountable problem even to experienced operators, particularly during periods of extremely variable weather as often occurs in the spring and the fall seasons.
Recently, attempts have been made to provide computerized control of the environment in poultry houses. For instance, U.S. Pat. No. Re. 33,600 to Timmons and U.S. Pat. No. 4,700,887 to Timmons disclose a computerized control system for a poultry house. Although in general computerized control systems for poultry houses have some merit, these systems are still in a stage of infancy and experimentation. Accurately controlling the temperature within poultry houses with these computerized control systems still presents many problems. For instance, because of the harsh environment, which includes extremely corrosive ammonia, sensors often fail and provide inaccurate temperature/humidity feedback signals to the computerized control systems. Also, the computerized control system and/or subsystems thereof typically fail because of the harsh environment without sufficient warning for remedial action to prevent extreme fluctuations in temperature/humidity, thereby adversely affecting the animals.
Still another problem with the prior art involves controlling ventilation and, specifically, the blowers. The blowers must be controlled to provide minimum ventilation requirements as a result of ammonia levels as well to modify the temperature/humidity in the poultry house, when necessary, in order to maintain an appropriate temperature/humidity for the animals. However, oftentimes, because of these dual responsibilities, the blowers are actuated too often or too little, thereby causing a drastic change in the temperature/humidity in the house.
Thus, a heretofore unaddressed need exists in the industry for systems and methods for insuring the integrity of sensed feedback signals which are representative of environmental conditions, such as temperature and humidity, within a poultry house and for optimally controlling the blowers within the poultry house to achieve both minimum ventilation requirements and a modification in temperature/humidity, when necessary.